Microsoft Security Bulletin MS14-052 - Critical

In this article

Cumulative Security Update for Internet Explorer (2977629)

Published: September 9, 2014 | Updated: December 19, 2014

Version: 1.1

General Information

Executive Summary

This security update resolves one publicly disclosed and thirty-six privately reported vulnerabilities in Internet Explorer. The most severe of these vulnerabilities could allow remote code execution if a user views a specially crafted webpage using Internet Explorer. An attacker who successfully exploited these vulnerabilities could gain the same user rights as the current user. Customers whose accounts are configured to have fewer user rights on the system could be less impacted than those who operate with administrative user rights.

The security update addresses the vulnerabilities by modifying the way that Internet Explorer handles objects in memory, and by adding additional permission validations to Internet Explorer. For more information about the vulnerabilities, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability entry later in this bulletin.

Recommendation. Most customers have automatic updating enabled and will not need to take any action because this security update will be downloaded and installed automatically. For information about specific configuration options in automatic updating, see Microsoft Knowledge Base Article 294871. For customers who do not have automatic updating enabled, the steps in Turn automatic updating on or off can be used to enable automatic updating.

For enterprise installations, or administrators and end users who want to install this security update manually (including customers who have not enabled automatic updating), Microsoft recommends that customers apply the update immediately using update management software, or by checking for updates using the Microsoft Update service. The updates are also available via the download links in the Affected Software table in this bulletin.

For additional guidance, see the Detection and Deployment Tools and Guidance section in this bulletin.

Knowledge Base Article

Affected and Non-Affected Software

The following software has been tested to determine which versions or editions are affected. Other versions or editions are either past their support life cycle or are not affected. To determine the support life cycle for your software version or edition, see Microsoft Support Lifecycle.

Update FAQ

I am running Internet Explorer 11 on Windows 8.1, Windows Server 2012 R2, or Windows RT 8.1. Why am I not being offered the 2977629 update?
To be offered any security updates on Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2, the 2919355 update must be installed on the system. For more information, see Microsoft Knowledge Base Article 2919355.

I am running Internet Explorer 11 on Windows 7 or Windows Server 2008 R2. Why am I not being offered the 2977629 update?
To be offered any security updates for Internet Explorer 11 on Windows 7 or Windows Server 2008 R2, update 2929437 must be installed on the system. For more information, see Microsoft Knowledge Base Article 2929437.

For Internet Explorer 11 are there any prerequisites for the 2977629 update?
Yes. Customers running Windows 8.1, Windows Server 2012 R2, or Windows RT 8.1 must first install the 2919355 update released in April, 2014 before installing the 2977629 update. For more information about the prerequisite update, see Microsoft Knowledge Base Article 2919355.

Customers running Internet Explorer 11 on Windows 7 or Windows Server 2008 R2, must first install the 2929437 update released in April, 2014 before installing the 2977629 update. For more information about this prerequisite update, see Microsoft Knowledge Base Article 2929437.

Does this update contain any additional security-related changes?
Yes. In addition to the changes that are listed for the vulnerabilities described in this bulletin, this update includes defense-in-depth updates to the Internet Explorer XSS Filter to help improve security-related features.

What is defense-in-depth?
In information security, defense-in-depth refers to an approach in which multiple layers of defense are in place to help prevent attackers from compromising the security of a network or system.

I am using an older release of the software discussed in this security bulletin. What should I do?
The affected software listed in this bulletin has been tested to determine which releases are affected. Other releases are past their support life cycle. For more information about the product lifecycle, see the Microsoft Support Lifecycle website.

Customers who require custom support for older software must contact their Microsoft account team representative, their Technical Account Manager, or the appropriate Microsoft partner representative for custom support options. Customers without an Alliance, Premier, or Authorized Contract can contact their local Microsoft sales office. For contact information, see the Microsoft Worldwide Information website, select the country in the Contact Information list, and then click Go to see a list of telephone numbers. When you call, ask to speak with the local Premier Support sales manager. For more information, see the Microsoft Support Lifecycle Policy FAQ.

Severity Ratings and Vulnerability Identifiers

The following severity ratings assume the potential maximum impact of the vulnerability. For information regarding the likelihood, within 30 days of this security bulletin's release, of the exploitability of the vulnerability in relation to its severity rating and security impact, please see the Exploitability Index in the September bulletin summary. For more information, see Microsoft Exploitability Index.

For example, Windows Clients: Critical / RCE specifies that the vulnerability is Critical severity with impact of remote code execution for the affected version of Internet Explorer running on a Windows client operating system. Windows Servers: Moderate / RCE specifies that the vulnerability is Moderate severity with impact of remote code execution for the affected version of Internet Explorer running on a Windows server operating system. Windows Clients:Important / Information Disclosure specifies that the vulnerability is Important severity with impact of information disclosure for the affected version of Internet Explorer running on a Windows client. Windows Servers: Low / Information Disclosure specifies that the vulnerability is Low severity with impact of information disclosure for the affected version of Internet Explorer running on a Windows server operating system. Windows Clients:Moderate / DOS or Windows Servers:Moderate / DOS specifies that the vulnerability is Moderate severity with impact of denial of service for the affected version of Internet Explorer running on a Windows client operating system or on a Windows server operating system.

An information disclosure vulnerability exists in Internet Explorer which allows resources loaded into memory to be queried. This vulnerability could allow an attacker to detect anti-malware applications in use on a target and use the information to avoid detection.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, click the link in the following table:

### Mitigating Factors
Microsoft has not identified any [mitigating factors](https://technet.microsoft.com/library/security/dn848375.aspx) for this vulnerability.
### Workarounds
Microsoft has not identified any [workarounds](https://technet.microsoft.com/library/security/dn848375.aspx) for this vulnerability.
### FAQ
**What is the scope of the vulnerability?**
This is an information disclosure vulnerability.
**What causes the vulnerability?**
This vulnerability is caused when the XMLDOM ActiveX control allows local resources to be enumerated, resulting in an information disclosure.
**What is XMLDOM?**
The XML Document Object Model (DOM) class is an in-memory representation of an XML document. The DOM allows you to programmatically read, manipulate, and modify an XML document. The XmlReader class also reads XML; however, it provides non-cached, forward-only, read-only access. This means that there are no capabilities to edit the values of an attribute or content of an element, or the ability to insert and remove nodes with the XmlReader. Editing is the primary function of the DOM. It is the common and structured way that XML data is represented in memory, although the actual XML data is stored in a linear fashion when in a file or coming in from another object.
**What might an attacker use this vulnerability to do?**
An attacker who successfully exploited this vulnerability could gain the same user rights as the current user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
**How could an attacker exploit this vulnerability?**
In a web-based attack scenario, an attacker could host a website that is used to attempt to exploit this vulnerability. In addition, compromised websites and websites that accept or host user-provided content could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to view the attacker-controlled content. Instead, an attacker would have to convince users to take action. For example, an attacker could trick users into clicking a link that takes them to the attacker's site.
**What systems are primarily at risk from this vulnerability?**
Systems where Internet Explorer is used frequently, such as workstations or terminal servers, are at the most risk from this vulnerability.
**What does the update do?**
The update addresses the vulnerability by limiting access to loaded resource data via XMLDOM.
**When this security bulletin was issued, had this vulnerability been publicly disclosed?**
Consult the following table:

Yes. Microsoft is aware of limited active attacks that attempt to exploit this vulnerability.

Multiple Memory Corruption Vulnerabilities in Internet Explorer
---------------------------------------------------------------
Remote code execution vulnerabilities exist when Internet Explorer improperly accesses objects in memory. These vulnerabilities could corrupt memory in such a way that an attacker could execute arbitrary code in the context of the current user.
To view any of these vulnerabilities as a standard entry in the Common Vulnerabilities and Exposures list, click a link in the following table:

### Mitigating Factors
Mitigation refers to a setting, common configuration, or general best-practice, existing in a default state that could reduce the severity of exploitation of a vulnerability. The following mitigating factors may be helpful in your situation:
- In a web-based attack scenario, an attacker could host a specially crafted website that is designed to exploit these vulnerabilities through Internet Explorer, and then convince a user to view the website. The attacker could also take advantage of compromised websites and websites that accept or host user-provided content or advertisements. These websites could contain specially crafted content that could exploit these vulnerabilities. In all cases, however, an attacker would have no way to force users to view the attacker-controlled content. Instead, an attacker would have to convince users to take action, typically by getting them to click a link in an email message or in an Instant Messenger message that takes users to the attacker's website, or by getting them to open an attachment sent through email.
- An attacker who successfully exploited these vulnerabilities could gain the same user rights as the current user. Customers whose accounts are configured to have fewer user rights on the system could be less impacted than those who operate with administrative user rights.
- By default, all supported versions of Microsoft Outlook, Microsoft Outlook Express, and Windows Mail open HTML email messages in the Restricted sites zone. The Restricted sites zone, which disables script and ActiveX controls, helps reduce the risk of an attacker being able to use these vulnerabilities to execute malicious code. If a user clicks a link in an email message, the user could still be vulnerable to exploitation of these vulnerabilities through the web-based attack scenario.
- By default, Internet Explorer on Windows Server 2003, Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, and Windows Server 2012 R2 runs in a restricted mode that is known as [Enhanced Security Configuration](http://technet.microsoft.com/library/dd883248). This mode mitigates these vulnerabilities. See the FAQ section for these vulnerabilities for more information about Internet Explorer Enhanced Security Configuration.
### Workarounds
Workaround refers to a setting or configuration change that does not correct the underlying vulnerability but would help block known attack vectors before you apply the update. Microsoft has tested the following workarounds and states in the discussion whether a workaround reduces functionality:
- **Configure Internet Explorer to prompt before running Active Scripting or to disable Active Scripting in the Internet and Local intranet security zone**
You can help protect against exploitation of these vulnerabilities by changing your settings to prompt before running Active Scripting or to disable Active Scripting in the Internet and Local intranet security zone. To do this, perform the following steps:
1. In Internet Explorer, click **Internet Options** on the **Tools** menu.
2. Click the **Security** tab.
3. Click **Internet**, and then click **Custom Level**.
4. Under **Settings**, in the **Scripting** section, under **Active Scripting**, click **Prompt** or **Disable**, and then click **OK**.
5. Click **Local intranet**, and then click **Custom Level**.
6. Under **Settings**, in the **Scripting** section, under **Active Scripting**, click **Prompt** or **Disable**, and then click **OK**.
7. Click **OK** two times to return to Internet Explorer.
**Note** Disabling Active Scripting in the Internet and Local intranet security zones may cause some websites to work incorrectly. If you have difficulty using a website after you change this setting, and you are sure the site is safe to use, you can add that site to your list of trusted sites. This will allow the site to work correctly.
**Impact of workaround.** There are side effects to prompting before running Active Scripting. Many websites that are on the Internet or on an intranet use Active Scripting to provide additional functionality. For example, an online e-commerce site or banking site may use Active Scripting to provide menus, ordering forms, or even account statements. Prompting before running Active Scripting is a global setting that affects all Internet and intranet sites. You will be prompted frequently when you enable this workaround. For each prompt, if you feel you trust the site that you are visiting, click **Yes** to run Active Scripting. If you do not want to be prompted for all these sites, use the steps outlined in "Add sites that you trust to the Internet Explorer Trusted sites zone".
**Add sites that you trust to the Internet Explorer Trusted sites zone**
After you set Internet Explorer to require a prompt before it runs ActiveX controls and Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to the Internet Explorer Trusted sites zone. This will allow you to continue to use trusted websites exactly as you do today, while helping to protect you from this attack on untrusted sites. We recommend that you add only sites that you trust to the Trusted sites zone.
To do this, perform the following steps:
1. In Internet Explorer, click **Tools**, click **Internet Options**, and then click the **Security** tab.
2. In the **Select a web content zone to specify its current security settings** box, click **Trusted Sites**, and then click **Sites**.
3. If you want to add sites that do not require an encrypted channel, click to clear the **Require server verification (https:) for all sites in this zone** check box.
4. In the **Add this website to the zone** box, type the URL of a site that you trust, and then click **Add**.
5. Repeat these steps for each site that you want to add to the zone.
6. Click **OK** two times to accept the changes and return to Internet Explorer.
**Note** Add any sites that you trust not to take malicious action on your system. Two in particular that you may want to add are **\*.windowsupdate.microsoft.com** and **\*.update.microsoft.com**. These are the sites that will host the update, and it requires an ActiveX Control to install the update.
- **Set Internet and Local intranet security zone settings to "High" to block ActiveX Controls and Active Scripting in these zones**
You can help protect against exploitation of these vulnerabilities by changing your settings for the Internet security zone to block ActiveX controls and Active Scripting. You can do this by setting your browser security to High.
To raise the browsing security level in Internet Explorer, perform the following steps:
1. On the Internet Explorer **Tools** menu, click **Internet Options**.
2. In the **Internet Options** dialog box, click the **Security** tab, and then click **Internet**.
3. Under **Security level for this zone**, move the slider to **High**. This sets the security level for all websites you visit to High.
4. Click **Local intranet**.
5. Under **Security level for this zone**, move the slider to **High**. This sets the security level for all websites you visit to High.
6. Click **OK** to accept the changes and return to Internet Explorer.
**Note** If no slider is visible, click **Default Level**, and then move the slider to **High**.
**Note** Setting the level to High may cause some websites to work incorrectly. If you have difficulty using a website after you change this setting, and you are sure the site is safe to use, you can add that site to your list of trusted sites. This will allow the site to work correctly even with the security setting set to High.
**Impact of workaround.** There are side effects to blocking ActiveX Controls and Active Scripting. Many websites that are on the Internet or on an intranet use ActiveX or Active Scripting to provide additional functionality. For example, an online e-commerce site or banking site may use ActiveX Controls to provide menus, ordering forms, or even account statements. Blocking ActiveX Controls or Active Scripting is a global setting that affects all Internet and intranet sites. If you do not want to block ActiveX Controls or Active Scripting for such sites, use the steps outlined in "Add sites that you trust to the Internet Explorer Trusted sites zone".
**Add sites that you trust to the Internet Explorer Trusted sites zone**
After you set Internet Explorer to block ActiveX controls and Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to the Internet Explorer Trusted sites zone. This will allow you to continue to use trusted websites exactly as you do today, while helping to protect yourself from this attack on untrusted sites. We recommend that you add only sites that you trust to the Trusted sites zone.
To do this, perform the following steps:
1. In Internet Explorer, click **Tools**, click **Internet Options**, and then click the **Security** tab.
2. In the **Select a web content zone to specify its current security settings** box, click **Trusted Sites**, and then click **Sites**.
3. If you want to add sites that do not require an encrypted channel, click to clear the **Require server verification (https:) for all sites in this zone** check box.
4. In the **Add this website to the zone** box, type the URL of a site that you trust, and then click **Add**.
5. Repeat these steps for each site that you want to add to the zone.
6. Click **OK** two times to accept the changes and return to Internet Explorer.
**Note** Add any sites that you trust not to take malicious action on your system. Two in particular that you may want to add are **\*.windowsupdate.microsoft.com** and **\*.update.microsoft.com**. These are the sites that will host the update, and it requires an ActiveX Control to install the update.
### FAQ
**What is the scope of the vulnerabilities?**
These are remote code execution vulnerabilities in the context of the current user.
**What causes the vulnerabilities?**
When Internet Explorer improperly accesses an object in memory, it could corrupt memory in such a way that an attacker could execute arbitrary code in the context of the current user.
**What might an attacker use the vulnerabilities to do?**
An attacker who successfully exploited these vulnerabilities could gain the same user rights as the current user. If the current user is logged on with administrative user rights, an attacker who successfully exploited these vulnerabilities could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.
**How could an attacker exploit the vulnerabilities?**
An attacker could host a specially crafted website that is designed to exploit these vulnerabilities through Internet Explorer, and then convince a user to view the website. The attacker could also take advantage of compromised websites and websites that accept or host user-provided content or advertisements. These websites could contain specially crafted content that could exploit these vulnerabilities. In all cases, however, an attacker would have no way to force users to view the attacker-controlled content. Instead, an attacker would have to convince users to take action, typically by getting them to click a link in an email message or in an Instant Messenger message that takes users to the attacker's website, or by getting them to open an attachment sent through email.
**What systems are primarily at risk from the vulnerabilities?**
Systems where Internet Explorer is used frequently, such as workstations or terminal servers, are at the most risk from these vulnerabilities.
**I am running Internet Explorer on Windows Server 2003, Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, or Windows Server 2012 R2. Does this mitigate these vulnerabilities?**
Yes. By default, Internet Explorer on Windows Server 2003, Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, and Windows Server 2012 R2 runs in a restricted mode that is known as [Enhanced Security Configuration](http://technet.microsoft.com/library/dd883248). Enhanced Security Configuration is a group of preconfigured settings in Internet Explorer that can reduce the likelihood of a user or administrator downloading and running specially crafted web content on a server. This is a mitigating factor for websites that you have not added to the Internet Explorer Trusted sites zone.
**Can EMET help mitigate attacks that could attempt to exploit these vulnerabilities?**
Yes. The Enhanced Mitigation Experience Toolkit (EMET) enables users to manage security mitigation technologies that help make it more difficult for attackers to exploit vulnerabilities in a given piece of software. EMET could help mitigate exploits against these vulnerabilities in Internet Explorer on systems where EMET is installed and configured to work with Internet Explorer.
For more information about EMET, see [The Enhanced Mitigation Experience Toolkit](http://technet.microsoft.com/security/jj653751).
**What does the update do?**
The update addresses the vulnerabilities by modifying the way that Internet Explorer handles objects in memory.
**When this security bulletin was issued, had these vulnerabilities been publicly disclosed?**
Consult the following table:

Yes, you must restart your system after you apply this security update.

Removal information

For Internet Explorer 6 for all supported 32-bit editions, x64-based editions, and Itanium-based editions of Windows Server 2003:
Use Add or Remove Programs item in Control Panel or the Spuninst.exe utility located in the Use the Spuninst.exe utility, located in the %Windir%\$NTUninstallKB2977629$\Spuninst folder

For Internet Explorer 7 for all supported 32-bit editions, x64-based editions, and Itanium-based editions of Windows Server 2003:
Use Add or Remove Programs item in Control Panel or the Spuninst.exe utility located in the %Windir%\ie7updates\KB2977629-IE7\spuninst folder

For Internet Explorer 8 for all supported 32-bit editions and x64-based editions of Windows Server 2003:
Use Add or Remove Programs item in Control Panel or the Spuninst.exe utility located in the %Windir%\ie8updates\KB2977629-IE8\spuninst folder

Yes, you must restart your system after you apply this security update.

Removal information

WUSA.exe does not support uninstall of updates. To uninstall an update installed by WUSA, click Control Panel, and then click Security. Under Windows Update, click View installed updates and select from the list of updates.

Yes, you must restart your system after you apply this security update.

Removal information

WUSA.exe does not support uninstall of updates. To uninstall an update installed by WUSA, click Control Panel, and then click Security. Under Windows Update, click View installed updates and select from the list of updates.

Yes, you must restart your system after you apply this security update.

Removal information

To uninstall an update installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, and then under Windows Update, click View installed updates and select from the list of updates.

Yes, you must restart your system after you apply this security update.

Removal information

To uninstall an update installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, and then under Windows Update, click View installed updates and select from the list of updates.

Yes, you must restart your system after you apply this security update.

Removal information

To uninstall an update installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, click Windows Update, and then under See also, click Installed updates and select from the list of updates.

Yes, you must restart your system after you apply this security update.

Removal information

To uninstall an update installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, click Windows Update, and then under See also, click Installed updates and select from the list of updates.